HVAC Engineering: Beginner CFD Training Package — Ep 07
Double Skin Façade
- Lesson
- 07
- Run Time
- 17m 15s
- Published
- Aug 6, 2026
- Category
- HVAC
- Course Progress
- 0%
Double Skin Façade — ANSYS Fluent CFD Simulation
Description
This project simulates airflow within a building's double-skin façade (DSF) using ANSYS Fluent. A double-skin façade is a building envelope with an air cavity between two layers, where solar-heated air rises by buoyancy — providing passive heating and aiding ventilation and cooling inside the building. The study evaluates the buoyancy-driven circulation set up within this cavity when the glazed outer layer absorbs solar energy. Within the HVAC Engineering: Beginner CFD Training Package, this project couples solar gain with buoyancy-driven airflow inside the building envelope, moving from single-room ventilation toward the behavior of the building skin itself.
Methodology
The three-dimensional geometry, built in DesignModeler, is a rectangular cavity measuring 0.6 × 3.2 × 5 m, composed of a duct for airflow and a glazed section that absorbs solar heat. The openings include a 0.2 m rectangular inlet at the bottom of the glass wall and a 0.2 m outlet near the top. Meshing in ANSYS Meshing yields 490,725 elements.
The glass section is modeled with a volumetric heat generation of 6,940 W/m³ to represent solar gain. The building walls are brick and subject to convection to the interior at T = 300 K with a heat-transfer coefficient of h = 23 W/m²·K (free convection). Supply air enters the façade at 304.55 K and atmospheric pressure. To capture the buoyancy effect, the air density follows the ideal-gas law and gravity of 9.81 m/s² is applied, so the temperature differences generated by the solar gain drive the flow.
Analysis
Post-processing provides 2D and 3D pressure, velocity, and temperature contours, along with 2D and 3D velocity vectors. The vectors show an upward flow within the cavity, confirming the buoyancy-driven ventilation within the double-skin façade. From these results you can evaluate how effectively the façade drives passive airflow, how the solar gain distributes heat through the cavity, and how the design contributes to ventilation and thermal regulation of the building.